Polyester melt blended compositions are well known in the art. U.S. Pat. No. 4,489,190 discloses compositions of an isotropic polyester, such as polyalkylene terephthalate, and a wholly aromatic liquid crystalline polyester. The above mentioned blend can be molded to form shaped articles and possesses satisfactory mechanical properties such as strength and stiffness. However, the wholly aromatic liquid crystalline polyesters are generally dispersed in a droplet shape in a polyalkylene terephthalate matrix, thus creating a composition having less strength and less stiffness than can be achieved by a polyalkylene terephthalate matrix reinforced by liquid crystalline polyesters in the shape of fibers.
It is known in the art that linear polyester-polyepoxide compounds may be blended under reactive conditions (typically involving extrusion) with at least one other linear polyester, such as a polyalkylene terephthalate, to form branched polyesters with favorable melt viscosities. However, these blended compositions lack the strength and stiffness of a linear polyester reinforced by a fibrous liquid crystalline polyester.
The present invention provides a stronger and stiffer composition having a linear polyester liquid crystalline polyester composition which exhibits less dripping. The liquid crystalline polyesters are not droplet shaped but rather are fibrillated acting to reinforce the polyalkylene terephthalate matrix. The composition exhibits a high degree of anisotropy in the melt phase and may be further reinforced by fibers or mineral fillers.